Add error messaging for x509 commit signing problems
<!--IssueSummary start--> <details> <summary> Everyone can contribute. [Help move this issue forward](https://handbook.gitlab.com/handbook/marketing/developer-relations/contributor-success/community-contributors-workflows/#contributor-links) while earning points, leveling up and collecting rewards. </summary> - [Work on this issue](https://contributors.gitlab.com/manage-issue?action=work&projectId=278964&issueIid=321703) - [Close this issue](https://contributors.gitlab.com/manage-issue?action=close&projectId=278964&issueIid=321703) </details> <!--IssueSummary end--> Currently if an x509 certificate used to sign a commit is in some way deficient, such as missing `crlDistributionPoints` or the like, then no error is raised and instead there's just a rather cryptically missing `Verified`/`Unverified` badge. If there is an issue with the certificate we should most likely generate a log message, and also consider an `Error` badge with details of the error in place of the `Verified`/`Unverified` badge. Related https://gitlab.com/gitlab-org/gitlab/-/issues/295297 Related https://gitlab.com/gitlab-org/gitlab/-/issues/293697
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